In recent years, a large number of vehicles such as an electric vehicle or a hybrid car driven by a motor are in practice. An operation sound of a motor is quiet compared with an operation sound of an internal combustion engine when such a vehicle is in operation. Accordingly, a pedestrian or the like may not feel existence of such a vehicle. In consideration of such a problem, for example, Publication of Japanese Unexamined patent application 10-201001 (JP-A-10-201001) and Publication of Japanese unexamined patent application 2006-199110, which corresponds to US Patent 20070257783, propose a vehicle existence informing device. Specifically, such a vehicle existence informing device causes an audio speaker equipped to a vehicle so as to generate a warning sound such as a dummy engine sound, thereby to inform a pedestrian ahead of the vehicle of existence of the vehicle.
It is noted that such a warning sound is diffused therearound while being attenuated when simply radiated. In addition, such a vehicle existence informing device is supposed to be in an outdoor use. Accordingly, a large scale audio speaker having a waterproofing structure is needed. Consequently, mountability of such a vehicle existence informing device is low. In addition, a manufacturing cost of such a vehicle existence informing device becomes high. Furthermore, when a warning sound is radiated from an audio speaker, such a warning sound is audible for a person such as an occupant of the vehicle who does not need to feel existence of the vehicle. Accordingly, such a person may feel uncomfortable.
Publication of Japanese unexamined patent application 2007-182195 proposes a vehicle existence informing device configured to radiate a warning sound and transmit an electric wave for warning. This vehicle existence informing device enables a person to feel existence of a vehicle in a tactile or visual manner when receiving the electric wave. However, in this case, a vehicle needs to be equipped with a transmitting device of an electric wave. In addition, a person needs to bring a receiving device for receiving an electric wave and a tactile device or the like activated when receiving an electric wave in order to feel existence of a vehicle by receiving an electric wave transmitted from the vehicle existence informing device. It is noted that a person may forget bringing of such a receiving device and a tactile device. In this case, the person may be incapable of feeling existence of a vehicle consequently.